"Okay," she says. "I think a good way to explain the basics might be: Over the course of human history, every so often, somebody has invented a way to do magic based on what made sense to them at the time or what they thought would work from hearing about other people's real or imagined successes. And some of these things, but not all of them, have turned out to actually work. And whenever somebody found one that did - and sometimes when they found one that didn't and just misinterpreted the results - they stuck with it and elaborated on it and taught it to other people who elaborated some more and forgot parts and changed details and generally messed around. And again, some of those changes stuck around, but not all of them, and the original methods usually weren't completely erased in the process. So now, after however many thousands of years of this, the state of the world's magic is an enormous clusterfuck. It would be like if the outcomes of scientific experiments were decided by rolling dice and the universe stuck to its guns on them afterward, occasionally even when they contradicted each other. That's basically the underlying foundations of magic."